1. Field of the Invention
The invention relates to sewing machine looptakers, and more particularly to arrangements for affixing a drive gear to a looptaker shaft.
2. Description of the Prior Art
It has been a common practice to secure a drive gear directly to the depending shaft of a sewing maching looptaker with a set screw as in the manner shown for example, in U.S. Pat. No. 3,242,891 for "Stitch Forming Drive Mechanism" of E. W. Bialy, issued Mar. 29, 1966, and in U.S. Pat. No. 3,693,566 for "Bobbin Thread Replenishing Mechanism for Sewing Machines" of S. J. Ketterer, issued Sept. 26, 1972.
In sewing machines provided with bobbin replenishing mechanism including a rotatable spindle within a hollow looptaker shaft as disclosed in the aforementioned U.S. Pat. No. 3,693,566, the use of a set screw for affixing a gear to the looptaker shaft is feasable if the shaft is of a material such as steel which is sufficiently resistant to deformation under the screw to prevent the shaft from being indented by the screw and interfering with the operation of the spindle. However, it is often desirable to use a material such as zinc or a plastic which is less resistant to localized pressure and with which the looptaker and shaft can be cheaply cast or molded into an integral structure requiring little or no machining.
It is a prime object of the present invention to provide the means for affixing a gear to a locally deformable cast or molded hollow looptaker shaft without affecting the freedom of movement of a spindle within the shaft.
It is another object of the invention to provide an arrangement enabling a drive gear to be secured to a hollow looptaker shaft with the turn of a set screw and without applying a localized pressure to the shaft under the screw.
Other objects and advantages of the invention will become apparent during a reading of the specification taken in connection with the accompanying drawings.